Field of the Invention
The present invention relates to an e-mail sending-receiving system, a control method therefor, an information processing apparatus, a control method therefor, and a storage medium storing control program therefor, and particularly relates to a technique for sending and receiving an e-mail including an attached file encrypted.
Description of the Related Art
When an E-mail including an attached file is sent, a password is set to the attached file for a purpose of ensuring security in many cases (see Japanese Laid-Open Patent Publication (Kokai) No. 2015-122097 (JP 2015-122097A)). In this case, the ZIP file format that allows compression of an attached file to reduce file size and enables to set a password is widely used from a viewpoint of ensuring security.
However, a user may forget encryption of an attached file when sending an e-mail or a user may not encrypt an attached file intentionally because an encryption operation is troublesome. In order to avoid a security risk at the time when an e-mail including an attached file that is not encrypted is sent, the above-mentioned publication has proposed a method that a mail server automatically sets a password and encrypts the attached file that was not encrypted.
However, since the method described in the above-mentioned publication aims to ensure the security at the time of sending of an e-mail including an attached file, a receiver of the e-mail needs to input the password for decoding the attached file, which requires labor. Moreover, since the decoded attached file is in a state where no password is set, there is a problem that the security is not ensured.